By using a computer, a player can play a Go game with the computer or another player via a network. Go is a game in which players compete for the size of one's territory, and it is important that the player establishes a strategy and makes a move by constantly considering what to do to keep one's living stones or to kill the opponent's stone in some situation.
For instance, if a player can determine (i.e., predict) that one's stone is dead in the early stage, the player can abandon said territory and concentrate on another place, which is very efficient as an overall strategy as well. For this reason, in Go, it is very important to determine (i.e., predict) whether one's stone or the opponent's stone is alive or dead. Note that whether a stone is alive or dead is referred to as the “life or death”. Furthermore, living stones are those that cannot be captured by the opponent's moves or those that, if captured, can create new stones that cannot be captured by the opponent; dead stones are those other than living stones, which can be captured by moves of the opponent.
Moreover, in addition to the strategy during a Go game, the life and death of stones must be determined also at the endgame; from this viewpoint as well, the life or death of stones is important. For this reason, there is also, what is called Tsumego, where players are challenged by a problem of life or death in a limited realm.
As such, in Go, it is extremely important to determine (i.e., predict) the life or death of stones; however, it is not easy to actually determine (i.e., predict) whether the stone is alive or dead. Particularly, it is difficult for a computer to do it automatically. Therefore, for instance, as shown in the following patent documents and non-patent documents, systems that perform the processing associated with life or death of stones are disclosed.